1. Technical Field
The present invention relates to a vibrator, an oscillator, a real-time clock, an electronic device and a moving object.
2. Related Art
Hitherto, a tuning fork type vibration element using a quartz crystal has been known. Such a vibration element includes a base portion and a pair of vibrating arms, and is configured to flexurally vibrate using a flexural reverse-phase mode (hereinafter, referred to as an X-axis reverse-phase mode) in which the pair of vibrating arms alternately repeat approach and separation to and from each other, when seen in plan view, as a main vibration. In addition, in the field of such a vibration element, various configurations for reducing the vibration leakage (loss of elastic energy leaking outside of the vibration element) of the main vibration have been disclosed. For example, JP-A-2002-261575 discloses that the vibration leakage of the main vibration is reduced by forming notches on both sides of the base portion. In addition, JP-A-2005-236563 discloses that the vibration leakage of the main vibration is reduced by lengthening a transmission path of the main vibration with the base portion formed in a frame shape, and providing the base portion with a vibration offset portion that cancels the main vibration. In addition, JP-A-2002-141770 discloses that the vibration leakage of the main vibration is reduced by providing a support portion extending out from the base portion and supporting the vibration element through the support portion, to thereby lengthen a transmission path of the main vibration. In addition, JP-A-2015-149592 discloses that since coupling between modes is strengthened in a case where the resonance frequency of the main vibration and the resonance frequency of inherent modes (unnecessary vibration modes) other than the main vibration are close to 1:1, the vibration leakage of the main vibration is reduced by weakening this coupling.
As described above, various inventions for reducing the vibration leakage have been disclosed, but all of the inventions are inventions for reducing the vibration leakage of a flexural vibration (main vibration itself) in a pure X-axis reverse-phase mode, or inventions relating to coupling in which the resonance frequencies of the main vibration and the unnecessary vibration are set to be in the vicinity of 1:1 due to the number of unnecessary vibration modes being limited to one. Such inventions do not disclose internal resonance with inherent modes (unnecessary vibration modes) other than the main vibration, particularly, the vibration leakage of the main vibration caused by a plurality of unnecessary vibration modes, and the vibration leakage of the main vibration caused by internal resonance except in the vicinity of a condition in which a resonance frequency ratio with respect to a singular unnecessary vibration mode is set to 1.